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Lecture 3: Comp Phys

Comparative Physiology USD Fall 2018 Dr. Kenneth Renner

What is a buffer? conjugate acid-base pair that prevents or minimizes changes in pH with the addition of small amounts of acid or base substances
Define pH? physical property of a solution determined by conjugate acid/base pair at equilibrium
The depletion of H+ ________ pH. increases
What happens when you add an acid to a system? the base reacts with the H+ and the equilibrium shifts to acid
What happens when you add a base to a system? the acid reacts with the OH- and the equilibrium shifts to base
What is the equation to calculate pH? pH=pKa+log [conjugate base]/[conjugate acid]
Why are buffers important? they are important for maintaining homeostasis
What is the pH of human plasma? 7.35-7.45
How is human plasma pH maintained? by weak salts, acids as conjugate pairs, bicarbonate system, phosphate buffering system
What is acidosis? pH below 7.35
What is alkalosis? pH above 7.45
What is an enzyme made of? proteins which are made of amino acids with ionizable groups
What is a zwitterion? ionic form of amino acids at pH 7
When are ionic groups of proteins lost? when peptide bonds are formed
What makes an amino acid basic or acidic? containing an additional ionizable group
What is crutial to enzyme function? the ionizable groups becuase they allow the protein chains to be linked or confromed in a particular shape
Define: enzyme biocatalytic protein; most efficient catalysts known
What are 3 unique features of enzymes? Efficiency, specificity, and regulation
define: efficiency (in terms of enzymes) enzymes can catalyze a reaction almost immediately
What is an example of enzyme efficiency? enzyme cholinesterase: breaks down acetyle choline almost immediately for muscle contractions
What is specificity? (in terms of enzymes)? most enzymes exhibit relative specificity i.e. catalyze the same type of reaction with realitively similar structured substances
What is an example of enzyme specificity? enzyme monoaminoxidase: catalyzes norepinphrine, serotonin, dopamine
What type of regulation do most enzymes use? allosteric regulation
What is allosteric regulation? enzymes bind on some region of the enzyme to alter active site so S is not recognized or enhavces the function
What are the two types of specificity? Relative specificity and absolute specificity
What is relative specificity? enzymes catalyze the same types of reactions with similar structured substances
What is absolute specificity? enzymes catalyze only one type of reaction with a specific substrate
What is an example of an enzyme that uses absolute specificity? glycerol kinase
Define: active site (in terms of enzymes) region of an enzyme that recognizes a given substrate and catalyzes the conversion of a substrate to a product
What happens to an enzyme during catalysis reactions? the reaction will start and end with the enzyme i.e. neither created nor destroyed
What are the 3 types of reactions at the active site? bond-strain catalysis, acid-base catalysis, and orientation catalysis
What is bond strain catalysis? S binds to enzyme which causes bond strain and increases the probability that the bond will break
What is acid-base catalysis? active site has an ionizable r-group and they interact as proton donors or acceptors
what is orientation catalysis? substrate is held in an orientation that optimizes/maximizes the probability of a reaction
What role does temperature play in reaction rates? higher temperatures may increase reaction rates
What happens to enzymatic reaction rates at low temperatues? at low temperatures the enzyme is cold inactiavated
In cold inactivated enzymes, the inactivation is ______. reversible
What happens to intermediate to high temperatures on enzymatic reactions? as the temperature increases, the conversion from S-P increases due to increase in kinetic activity
What hapens to enzymatic reaction rates at extremely high temperatures? enzyme activity completely stops because the enzyme is denatured
In high temperature inactivated enzymes, the inacivation is _______. irriversible
What role does pH play in enzymatic reactions? most reactions have an optimum pH at which the reaction rate is at it's most efficient
What does altering pH from optimum do? effects the ionizable groups of amino acids that will make up the enzyme i.e. affect confirmation and alter recognition of the substrate
What do many enzymes depend on for optimum activity or presence of activity? cofactors
What are cofactors? non-protein substance
What is an enzyme in the absens of a cofactor/ with low or no activity? apoenzyme
What is an enzyme in the presence of a cofactor? haloenzyme
What are the two categories of cofactors? inorganic and organic
What are inorganic cofactors? usually ions, Zn2+,Mg2+,Fe2+, Ca2+
What are organic cofactors? often derived from vitamins, NAD+
What are organic cofactors often called? coenzymes
Define: vitamins essential nutrients not derived endogenously
What are fat soluble vitamins? A,E,D
What are water soluble vitamins? B series
How many role sdo cofactors have? 2
What is the first role of cofactors? alter substrate or enzyme conformation to maximize interaction
What is the second role of cofactors? participate in reaction as a second substrate by doating or accepting a particular chemical grouping
Enzymes can be ______ by both physiological and pharmacological agents inhibited
What are the two types of pharmacological enzyme inhibitors? irreversible inhibitors and reversible inhibitors
What are irriversible inhibitors? inhibitors that bind to the active site and are not released
What is an example of an irriveresible inhibitor? organophosphate nerve gas
How do orgnaophosphate nerve gases work? blocks the reaction
What are reversible inhibitors? inhibitors that may be removed
What are the two types of reversible inhibitors? competitive inhibitors and noncompetitive inhibitors
What are competitive inhibitors? reversible inhibitors that bind to the active site, but can be displaced in the presence of high substrate concentrations
What are noncompetitive inhibitors? reversible inhibitors that bind the enzyme outside of the active site and cause an allosteric or conformational change that alters active sites
How are noncompetitive inhibitors reversed? they are reversed as the inhibitor is released and degrated
Created by: kenzigustafson
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